Tall buildings can be viewed as valuable pieces of real estate, works of art or symbols of prestige. For David Malott, founding partner in the New York-based architectural firm AI and former Chairman of the Council on Tall Buildings and Urban Habitat (CTBUH), they're nothing less than humanity's future.
“From a planetary perspective, as the world's population grows, we need to compact the footprint of civilization,” he says.
Urbanization, Malott points out, continues to be the global trend. Even in the developed world, cities that were once defined by post-manufacturing blight are now seeing a renaissance as they become hubs for technology and service-based economies. “People want to live in the cities again. That's where the energy is. That's where the opportunities are.”
As these newcomers move in, the most energy-efficient and cost-effective way to accommodate them and the business they bring is vertically, in tall and supertall buildings (over 300m) with direct links to transport and other infrastructure, says Malott. That has already led to the ramping up of high rise construction as well as a massive interest among technologists in ways to build taller, smarter and more user-friendly buildings than ever before.
“I think we're still just at the beginning of it all. There are more tall buildings built in the last 20 years than in the preceding 100 years, and the pace of it only seems to be accelerating. The overall trajectory is one of moving upwards, not outwards,” he said.
In terms of engineering, Malott says, we can soon achieve buildings that are a mile high (1,600 m) using the same fundamental technology that has been in use for the past 40 years. Incremental improvements in steel and concrete, the construction materials of choice, have been nudging the height ceiling upward over the decades, but now surpassing the current threshold would require what he calls a “quantum leap in innovation.”
Malott cites the advent of KONE UltraRope, a carbon-fiber replacement for steel elevator cable, as one such leap.
He believes that other radical advances, only a year or two away, will similarly involve moving from steel and concrete to organic, carbon-based materials. One example is the renewed interest in wood, specifically wood combined with concrete to make composite structures, as a construction material for tall buildings. It has already been used to create buildings of up to 20 stories, he says.
Likewise, advances have been made in using crushed mushroom stems mixed with wood chips as a hardened, insulating material. Malott predicts that further in the future, perhaps in a couple of decades, buildings will feature bacteria-infused fabrics that can respond to heat by becoming porous.
“It's much more sustainable to grow materials instead of mining materials, and it's more sustainable to spin fabrics together into stronger structures than it is to melt steel,” he says.
“I want to heal and repair our planet because we're beyond the point of simply sustaining what we have. We have to do something radically different. Growing and harvesting buildings is definitely going to be something of the future.”
SKY'S THE LIMIT?
In the world of tall buildings, advances in construction materials and design software are certainly set to push the height boundaries ever further, a process that will drive innovation as designers are forced to work around new problems. But is that a good strategy? At what altitude will enough be enough?
“There might always be a desire to create icons and something taller than existed before, but at a certain point it's not what we need,” says Malott. He doesn't believe that the mainstream of our future lies in these gargantuan projects, but rather in clusters of buildings in the 300 to 500m range.
As he explains, the efficiency gains derived from densely packing people into a skyscraper are offset as other problems arise, among them the need for users to take two or more elevator rides to reach the upper floors.
Other limitations are psychological and physiological. For example, occupants of upper floors often feel claustrophobic because they can't open windows and access the outdoors. To get around this, architects need to design sky gardens and other outdoor spaces at height that are protected from the wind. Fire evacuation is another issue when too many flights of stairs are involved. Buildings can be designed in a compartmented way that will make evacuation unnecessary, but that still might not make occupants feel safe.
Fortunately, development in tall buildings isn't just about setting new height records, but involves making the buildings themselves more capable with the help of improved computer power.
Malott predicts that, as machine learning and AI advance, the computers that were once the tools of the architect will become better than the architect at carrying out repetitive design work. The role of the architect will then shift to focus on user experience, a factor that itself will get a boost from improved sensor technology. An abundance of sensors, which are now cheaper and better than ever, will act as a building's central nervous system, Malott believes, making it far more responsive than before.
Not only will the building be able to measure and adjust for changes in light or check structural soundness, but also get to know its users, providing each with a customized experience, Malott says. “There's going to be a more intimate connection between building and user. Just like with our apps and our music, buildings will be able to tailor themselves to each individual user, and that is going to be a game changer.”